Printed circuit board (PCB) design is becoming increasingly complex due to a variety of factors. Such factors include increasing data rates of signals conveyed by printed circuit boards, increasing numbers of I/O signals per integrated circuit, decreasing sizes of printed circuit boards and integrated circuits, decreasing space between integrated circuits on printed circuit boards, increasing numbers of layers within printed circuit boards, and increasing printed circuit board thickness. Many of these factors lead to increasing trace and via density within printed circuit boards.
Due to the combination of increases in trace and via density increases and as increases in signal data rates, traces and vias are experiencing increased amounts of crosstalk. Crosstalk occurs when signals being routed by neighboring signal lines interfere with each other. Crosstalk leads to increased signal noise, and this noise makes it more difficult for a receiver to correctly interpret the signal.
In the past, crosstalk has been reduced by maintaining an amount of separation or isolation between traces and vias such that the crosstalk between signals conveyed by those traces and vias was minimized. Vias can be isolated by creating a virtual ground plane between vias. Typically, it is easier for designers to provide more space and/or more isolation between traces than it is between vias, especially in areas of high via density, such as the area underneath a set of ball grid array connectors used to couple an integrated circuit to the printed circuit board. Accordingly, it is desirable to be able to decrease the crosstalk between vias in a printed circuit board.